Engrailed is a ubiquitous transcriptional regulator that is potentially of great significance to human health. It has recently been linked to fate determination and survival of midbrain dopaminergic neurons, with En knockout mice showing Parkinson-like symptoms, and has also been linked to autism spectrum disorder. It is therefore essential to understand the role En plays in regulating neuronal connectivity. The long term objectives of this research are to use simple model systems, that have identifiable neurons, to investigate how Engrailed controls synaptic target recognition, and what are the downstream effector genes that it regulates. My previous work has used the cockroach cereal system to study this;however, there are substantial barriers to further progress in this system. The aims of this pilot project will enable me to develop a similar system of identifiable Engrailed-expressing neurons in the genetically tractable Drosophila melanogaster. The first aim is to use Gal4-UAS to express green fluorescent protein in neurons that normally express Engrailed. Confocal microscopy will then be used to characterize these neurons in a range of sensory systems, such as the olfactory, auditory and touch cells. The second aim is to focus on one of these sensory systems using the electrophysiological and anatomical techniques that have been developed in the lab, and the expertise of the mentor, Dr. Rod Murphey, in order to be able to test the role of Engrailed in controlling the synaptic connectivity of this system. The third aim will involve the co-expression of ectopic Engrailed along with GFP, enabling a direct test of the idea that Engrailed controls connectivity in the circuit. In the final aim, with the help of Dr. Rod Murphey, I will use genetic screens to begin a search for other genes downstream of Engrailed that control synaptic specificity. An alternative strategy will be to test En binding targets previously identified by other groups. Drosophila models are particularly useful for the discovery of molecular pathways that are directly relevant to human health, because most of these pathways have been conserved during evolution. All animals have Engrailed protein, so it is very likely that any molecules that are regulated by it during the process of synapse formation in Drosophila have their counterparts in humans. These molecules may be of great potential importance in neurological diseases such as Parkinson's or autism.